"STUDY OF AIR-COOLING SOLUTIONS FOR LITHIUM-ION BATTERIES IN HYBRID ELECTRIC VEHICLE BATTERY PACKS THROUGH TRANSIENT THERMAL ANALYSIS"

Abstract

A class of rechargeable battery types known as lithium-ion batteries transfer lithium ions from the negative electrode to the positive electrode during discharge and back again during charging. The different varieties of lithium-ion batteries have different chemistry, performance, cost, and safety properties. In order to ensure that the temperature of batteries is operating within a constrained optimal range and to provide solutions for cooling systems that are both cost- and energy-efficient, thermal modeling—the primary problem in thermal management of lithium-ion battery systems—must be carefully investigated. The focus of the current work is on historical cooling techniques, particularly forced convection via air, which is commonly used in thermal modelling of battery modules and packs. Design modification on the currently using lithium-ion batteries is done to improve the efficiency of heat transfer. Later on FEM analysis is done for steady state and transient thermal heat transfer on modified design of lithium-ion batteries. The analysis had to take into account the thermally critical working conditions under steady state. The boundary conditions were the heat flow of 0.138 W and the heat transfer coefficient for NMC material of 5.1 W/m/K and ambient temperature 45oC.In the context of transient thermal analysis, the entire amount of time is 3600 sec, with the first time step being 180 sec. Convection is regarded as the heat transfer mechanism in the peak of summer in the Jabalpur region, the ambient temperature was taken to be between 295.15 and 318.150 K with a heat transfer coefficient was varied between 0 to 30 W/m/0 K. Heat flow was also considered to be time-dependent, varying from 0.138 W to 0.667 W. The temperature distribution over the cell body, the total heat flow, and the directional heat flux were all observed under the aforementioned conditions, and the findings were presented. Results from two different arrangements were examined to determine which arrangement was preferable. In example I, 3X3 cell arrangements without an air gap were taken into consideration; in case II, a 3X3 cell arrangement with an air gap was being evaluated for investigation. Both of these situations were taken into consideration for examination under steady state and transient thermal real operating conditions, and the results were compared. Under steady state condition, it was noted that Case II's highest and minimum temperatures, respectively, were 29.5820 C and 29.4870 C. The steady state thermal investigation revealed a significant temperature difference of 30.460C between the two cases. Under transient thermal heat transfer condtion, the maximum temperature drop in Case 2—which took into account a cell with an air gap—was 0.4780 C, while the minimum temperature drop was 0.1270 C. the greater temperature reduction for scenario II (36000 sec) with respect to time. The overall effective surface area increased as a result of the air gap, which causes the aforementioned occurrence. Hence, it may be said that instance II's heat dissipation is superior to case I's. In case 2, the heat flux ranged from 366.42 W/m2 at maximum to -1.1528 W/m2 at minimum. In case 1, the heat dissipation ranged from 162.08 W/m2 to 90.033 W/m2, while in case 2, it ranged from 162.9 W/m2 to 39.4 W/m2. The data so make it very evident that Case II is more successful than Case I. Hence, case II is a better configuration.